Oh dear, I thought this would happen. Google in their constant quest to keep give us useful information have added a "public transportation layer" to some of their city maps. Here is the one for London, England.
It is a mess.
I am a local and familiar with the London Underground and find this representation unusable.
Fortunately we have had a simple and intuitive map which was first produced in 1931 by Harry Beck. The history is summarised in this Wikipedia article called Tube map . A superb example of JustEnoughTechnology
In addition to this elegant piece of design London has a comprehensive and interactive transport website
Transport for London which integrates all the transport options for travel in this city.
In this case Google have produced a technical solution rather than a useful one.